Food, feeding and growth of the eel (Anquilla anguilla L.) in a Dutch eutrophic lake

This thesis describes the food, foraging and growth of the eel (Anguilla anguilla). Attention is paid to the abundance and distribution of the food organisms and the feeding and growth of other fish species. The investigations were carried out in the Tjeukemeer (21 km2) in the northern part of the Netherlands. This lake is the main object of study of the Tjeukemeer laboratory, part of the Limnological Institute of the Royal Netherlands Academy of Arts and Sciences. The Royal Academy funded the research on eel, the Ministry of Health and the Environment funded the zooplankton research.The Tjeukemeer is a shallow (1-2 m) , turbid (Secchi-disc 0.30 - 0.40 m), hypertrophic lake. It is part of a system of canals and reservoirs (lakes) receiving surplus water in late autumn, winter and early spring from a watershed covering 3060 km 2. Via this system the water is drained into the Waddensea or pumped into the IJsselmeer. When during spring and summer the evaporation exceeds precipitation, the whole system is drained with water from the IJsselmeer. These inputs have great impact on the physico-chemical conditions, but also on the fish fauna of the lakes. The smelt (Osmerus eperlanus) immigrates passively from the IJsselmeer as a massive flow of larvae. This immigration is dependent on weather conditions, therefore the abundance of the smelt is highly variable.The shoreline of the Tjeukemeer is poorly developed, the emergent vegetation covers 0.5% of the surface; since the early 1970s the submerged aquatic vegetation is greatly reduced and now virtually absent.The eel population in the Tjeukemeer, like in other large Dutch lakes, is heavily exploited. The population is dominated by small eels between 200 and 300 mm. Eels smaller than 120 mm are scarce. The proportion of eels larger than 300 mm ranges between 7 and 30% of the catch.Irrespectively their body length, the eels prefer as food invertebrates, at least 7 mm large, living on the water bottom surface. In the Tjeukemeer the larvae (later instars) and pupae of the chironomids Chironomusplumosus , Einfeldiacarbonaria and Glytotendipespallens , and the amphipod Gammarustigrinus are most frequently consumed.In 1979 larger bivalve mollusks are of secondary importance in the eel diet, while in 1980 and 1981 the>200 mm eels can switch to predation on smelt ( O. eperlanus ). Eels smaller than 340 mm become gape- limited in predation on smelt because the smelt grows faster than the eel mouth.The searching and catching behaviour of small eels foraging on chironomids was investigated in aquaria. The feeding efficiency, expressed as the time interval between finding and swallowing the larva, rapidly decreases when larvae are burrowed in the substrate. The eel has no preference for pupae, if larvae and pupae are offered in the same way, i.e. both easily available for the eels.In the stomach contents of the eels from the lake the proportion of pupae in the total chironomid biomass is 60-90%. The preference for pupae is explained by the availability of pupae, in comparison with the chironomid larvae, which are often deeply burrowed in the bottom substrate.The growth of eel was investigated by means of otolith readings and cohort analysis. The otoliths from 905 eels were sawn and polished or manually ground to determine the age by counting winter rings. The growth of Earlier studies on fish and zooplankton showed the great impact of the predation by smelt on the density of the Daphnia , in the crustacean zooplankton. Daphnia also is an important part of the diet of larger bream ( A. brama ) . In 1980 and 1981, when the smelt population increases, the zooplankton is hardly available to the bream. A large part of the bream population switches to a diet of chironomids. The chironomid population becomes overexploited.The overexploitation of the chironomids caused bad feeding conditions for eels confined to prey on invertebrates. The low growth rate of small eels is explained by these feeding conditions. We observe that even small eels start to prey on smelt in 1980 and 1981, but become gape-limited. Larger eels (>340 mm) show a better growth when feeding on fish.The effects of the inputs of water from other origins in the Tjeukemeer on the horizontal distribution of crustacean zooplankton were studied. Only during short periods in summer, the population densities appeared to be influenced by the inflow of water from the IJsselmeer. In periods with a precipitation surplus (autumn and winter) the zooplankton community was "diluted" by the inflow of surplus water from the watershed. The influence on the rest of the aquatic fauna of the lake was only slight.Patchiness in the zooplankton distribution occurs in the Tjeukemeer due to inhomogeneities in physico-chemical parameters. However, the lake is shallow and strongly influenced by windinduced turbulence. The zooplankton appears to be more homogenous than in other lakes elsewhere in Europe. These lakes were often deeper or contained more sheltered parts.In the last chapter the role of the eel in the ecosystem is discussed. Although competition between eel and bream for food (chironomids) occurs, it is suggested that changes in the vegetation and nutrient loading of the lake and the heavy commercial exploitation of the eel population have a negative influence on the amount of eel, while the bream is favoured by the effects of eutrophication.</TT

Cell adhesion molecules nectins and associating proteins: Implications for physiology and pathology

Nectins have recently been identified as new cell adhesion molecules (CAMs) consisting of four members. They show immunoglobulin-like structures and exclusively localize at adherens junctions (AJs) between two neighboring cells. During the formation of cell–cell junctions, nectins function in cooperation with or independently of cadherins, major CAMs at AJs. Similar to cadherins, which are linked to the actin cytoskeleton by binding to catenins, nectins also bind to afadin through their C-terminal region and are linked to the actin cytoskeleton. In addition to nectins, there are nectin-like molecules (Necls), which resemble nectins in their structures and consist of five members. Nectins and Necls are involved in the formation of various kinds of cell–cell adhesion, and also play key roles in diverse cellular functions including cell movement, proliferation, survival, and differentiation. Thus, nectins and Necls are crucial for physiology and pathology of multicellular organisms

Partial Wave Analysis of J/ψ→γ(K+K−π+π−)J/\psi \to \gamma (K^+K^-\pi^+\pi^-)

BES data on $J/\psi \to \gamma (K^+K^-\pi^+\pi^-)$ are presented. The $K^*\bar K^*$ contribution peaks strongly near threshold. It is fitted with a broad $0^{-+}$ resonance with mass $M = 1800 \pm 100$ MeV, width $\Gamma = 500 \pm 200$ MeV. A broad $2^{++}$ resonance peaking at 2020 MeV is also required with width $\sim 500$ MeV. There is further evidence for a $2^{-+}$ component peaking at 2.55 GeV. The non-$K^*\bar K^*$ contribution is close to phase space; it peaks at 2.6 GeV and is very different from $K^{*}\bar{K^{*}}$.Comment: 15 pages, 6 figures, 1 table, Submitted to PL

Development of lanthanum strontium cobalt ferrite composite cathodes for intermediate- to low-temperature solid oxide fuel cells

Solid oxide fuel cells (SOFCs) offer high energy conversion, low noise, low pollutant emission, and low processing cost. Despite many advantages, SOFCs face a major challenge in competing with other types of fuel cells because of their high operating temperature. The necessity to reduce the operational temperature of SOFCs has led to the development of research into the materials and fabrication technology of fuel cells. The use of composite cathodes significantly reduces the cathode polarization resistance and expands the triple phase boundary area available for oxygen reduction. Powder preparation and composite cathode fabrication also affect the overall performance of composite cathodes and fuel cells. Among many types of cathode materials, lanthanum-based materials such as lanthanum strontium cobalt ferrite (La1-xSrxCo1-yFeyO3-δ) have recently been discovered to offer great compatibility with ceria-based electrolytes in performing as composite cathode materials for intermediate- to low-temperature SOFCs (IT-LTSOFCs). This paper reviews various ceria-based composite cathodes for IT-LTSOFCs and focuses on the aspects of progress and challenges in materials technology

Defeitos congênitos em bovinos da Região Central do Rio Grande do Sul

Foram revisados casos de defeitos congênitos (DCs) diagnosticados em bovinos no Laboratório de Patologia da Universidade Federal de Santa Maria em 1964-2010. Durante o período estudado, foram examinados materiais provenientes da necropsia de 7.132 bovinos e foram encontrados 31 bezerros (0,4%) com DCs, os quais foram classificados em 34 tipos e alocados nos sistemas orgânicos primariamente afetados. Os DCs ocorriam isoladamente (19 [61,3%]) ou afetavam múltiplos sítios anatômicos (15 [28,7%]) com frequência semelhante em ambos os sexos. Como vários terneiros mostraram múltiplos DCs, um total de 53 DCs foi computado. Dos 53 DCs diagnosticados, 15 (28,3%) afetavam o sistema nervoso central (craniósquise [4], abiotrofia cerebelar [2], degeneração esponjosa [2], hidrocefalia [2], meningocele [2], espinha bífida [1], hipoplasia cerebelar [1] e hipomielinogênese [1]); nove (17,0%) afetavam o sistema urogenital (agenesia testicular [1], agenesia vaginal [1], hipoplasia peniana [1], formação de cloaca [1], freemartinismo [1], hamartoma vascular de ovário [1], hipoplasia renal [1], cistos renais [1] e úraco persistente [1]); oito DCs (15,1%) eram primários do sistema musculoesquelético (artrogripose [4], escoliose [1], plagiocefalia, [1] schistosomus reflexus [1] e diprosopia [1]); e outros oito (15,1%) foram alocados no sistema digestivo (palatosquise [3], atresia anal [1], atresia anorretal [1], atresia - anocolônica [1], fístula reto-vaginal [1] e fístula reto-uretral [1]); em cinco ocasiões (9,4%) o DC afetava o sistema cardiovascular (persistência do ducto arterioso [2], persistência do forame oval [2] e defeito do septo ventricular [1]); quatro (7,5%) afetavam o sistema linfático e consistiam de hipoplasia ou aplasia de vasos linfáticos e linfonodos associadas a linfedema. Dois casos (3,4%), de hipotricose foram observados afetando o integumento; um caso (1,9%) de estenose traqueal foi encontrado no sistema respiratório e um caso (1,9%) de bócio envolvia o sistema endócrino. Os resultados indicam que a maioria dos DCs em bovinos na Região Central do Rio Grande do sul é esporádica. No entanto, seu estudo continuado é importante para o estabelecimento de sua etiologia e controle

Early carboniferous brachiopod faunas from the Baoshan block, west Yunnan, southwest China

38 brachiopod species in 27 genera and subgenera are described from the Yudong Formation in the Shidian-Baoshan area, west Yunnan, southwest China. New taxa include two new subgenera: Unispirifer (Septimispirifer) and Brachythyrina (Longathyrina), and seven new species: Eomarginifera yunnanensis, Marginatia cylindrica, Unispirifer (Unispirifer) xiangshanensis, Unispirifer (Septimispirifer) wafangjieensis, Brachythyrina (Brachythyrina) transversa, Brachythyrina (Longathyrina) baoshanensis, and Girtyella wafangjieensis. Based on the described material and constraints from associated coral and conodont faunas, the age of the brachiopod fauna from the Yudon Formation is considered late Tournaisian (Early Carboniferous), with a possibility extending into earlyViseacutean.<br /

Search for the Chiral Magnetic Effect in Au+Au collisions at sNN=27\sqrt{s_{_{\rm{NN}}}}=27 GeV with the STAR forward Event Plane Detectors

A decisive experimental test of the Chiral Magnetic Effect (CME) is considered one of the major scientific goals at the Relativistic Heavy-Ion Collider (RHIC) towards understanding the nontrivial topological fluctuations of the Quantum Chromodynamics vacuum. In heavy-ion collisions, the CME is expected to result in a charge separation phenomenon across the reaction plane, whose strength could be strongly energy dependent. The previous CME searches have been focused on top RHIC energy collisions. In this Letter, we present a low energy search for the CME in Au+Au collisions at $\sqrt{s_{_{\rm{NN}}}}=27$ GeV. We measure elliptic flow scaled charge-dependent correlators relative to the event planes that are defined at both mid-rapidity $|\eta|<1.0$ and at forward rapidity $2.1 < |\eta|<5.1$. We compare the results based on the directed flow plane ($\Psi_1$) at forward rapidity and the elliptic flow plane ($\Psi_2$) at both central and forward rapidity. The CME scenario is expected to result in a larger correlation relative to $\Psi_1$ than to $\Psi_2$, while a flow driven background scenario would lead to a consistent result for both event planes[1,2]. In 10-50\% centrality, results using three different event planes are found to be consistent within experimental uncertainties, suggesting a flow driven background scenario dominating the measurement. We obtain an upper limit on the deviation from a flow driven background scenario at the 95\% confidence level. This work opens up a possible road map towards future CME search with the high statistics data from the RHIC Beam Energy Scan Phase-II.Comment: main: 8 pages, 5 figures; supplementary material: 2 pages, 1 figur